Data produced by X-ray diffractometers is conventionally collected using a moving receiving slit. In the mostly commonly used mode of diffraction data collection, step scanning is employed to determine the spatial distribution of the radiation intensity (also referred to as the the so-called 2.THETA.profile, wherein .THETA.is the Bragg angle) and the receiving slit is moved to a new value of 2.THETA.for each step of the scanning operation, with the number of X-ray counts being measured and recorded for each step. In a variation of this method, Debye-Scherrer X-ray optics are used, particularly in microdiffractometer instruments. In Debye-Sherrer arrangements, the 28 scanning is provided by moving an annular receiving slit along the axis of the diffractometer. As will be appreciated, the need to move a receiving slit places a number of limitations on prior art diffractometers, including problems of alignment and tracking, and adds to the general overall complexity of the instrument.
Diffractometers in general, and diffractometers which employ moving receiving slits in particular, are fully described in the literature. Patents of possible interest insofar as the present invention is concerned include the following U.S. Pat. Nos. 4,696,024 (Pesch); 4,140,904 (Poot, et al.); 3,411,000 (Schliephake, et al.); 3,852,594 (Paolini); and 3,327,114 (Diorio, et al.). Briefly considering these patents, the Pesch Patent discloses a gamma diffractometer device used in studying imperfections in single crystals. A conventional scanning method is employed wherein the Bragg angle is varied and the diffracted radiation beams (gamma rays) are admitted to a radiation detector through a shutter operated receiving slit or slot. The Schliephake, et al. patent discloses a diffractometer accessory for controlling the width of an incident X-ray beam falling on a sample during scanning of a conventional X-ray diffractometer. The Paolini patent discloses a similar device. The Poot, et al. patant discloses a Debeye camera for powder samples which is capable of providing multiple samples on a single sheet of X-ray film. The Diorio patent discloses a low angle X-ray scattering device using a collimating arrangement, ccmprising series of apertures, for reducing the angular divergence of a primary X-ray beam.